At present, as high-speed transportation carriers such as high-speed railways are constantly built, commissioned, and put into use, the issue of high-speed information transmission between the next-generation mobile communications system and users in high-speed movement needs to be considered.
In high-speed movement, the large Doppler frequency shift that is generated makes, for example, long term evolution-time division duplex (LTE-TDD, Long Term Evolution-Time Division Duplex) downlink channels produce fast changes. Fast changing channels damage the orthogonal nature between subcarriers of the orthogonal frequency division multiplexing system, leading to inter-channel interference (ICI, Inter-channel interference). The channel changes between symbols produce time selective fading, lowering the system performance. When the pilot insertion mode and density are not changed, the fast changing channels lower the channel estimation precision of the existing channel estimation method of least square (LS, Least Square)+linear interpolation, and degrade the system performance.
Precise channel estimation is an important basis for performing interference cancellation between subcarriers, overcoming time selective fading, and improving balanced system performance. As the practice shows, the existing channel estimation method (LS+linear interpolation) may obtain favorable channel estimation precision when being applied to a slow fading channel environment, but generally cannot obtain channel estimation precision that meets communications needs when being applied to a fast time-changing channel environment such as high-speed railway, thereby affecting the system performance.